Doctor Who season 16

Doctor Who: The Key to Time
Season 16
File:The Key to Time DVD cvr.jpg Cover of the 2008 Region 2 DVD release
No. of episodes	23
Release
Original network	BBC One
Original release	3 September 1978 (1978-09-03) – 24 February 1979 (1979-02-24)
Season chronology

The Key to Time is the umbrella title that links all six serials of Season 16 of Doctor Who. The arc was originally conceived of by producer Graham Williams, who had proposed it as part of his application for the producer's job in 1976. The name refers to the powerful artifact whose segments the Doctor, Romana and K-9 are searching for during the season.

Synopsis

The Fourth Doctor is recruited by The White Guardian to seek out an unimaginably powerful artifact called the Key to Time. This key was an incredibly powerful device that could be used to control history on a large scale throughout the universe. To keep this device from being abused the Key to Time was broken into six indestructible pieces that were hidden throughout both time and space. The quest to retrieve these pieces is each a complete self-contained plot arc.

Casting

Tom Baker continued his role as The Fourth Doctor, and saw the introduction of Romana I played by Mary Tamm.

Episodes

Douglas Adams took over as script editor from Anthony Read for The Armageddon Factor. Season 16 consists of one long story arc encompassing six separate, linked stories.

Story No.	Serial	Title	Directed by	Written by	UK viewers (million)	Original air date	Production code
098	1	"The Ribos Operation"	George Spenton-Foster	Robert Holmes	8.1	2-23 September 1978	5A
The Doctor is recruited by the White Guardian to seek the six segments of the Key to Time. The quest for the first segment takes them to Ribos, a medieval planet that galactic confidence trickster Garron is trying to sell to the Graff Vynda-K.
099	2	"The Pirate Planet"	Pennant Roberts	Douglas Adams	8.3	30 September - 21 October 1978	5B
The quest for the second segment takes them to the planet Zanak, which has been hollowed out and fitted with hyperspace engines, allowing its insane half-robot Captain to materialise it around other smaller planets and plunder their resources.
100	3	"The Stones of Blood"	Darrol Blake	David Fisher	8.0	30 September - 21 October 1978	5C
The quest for the third segment takes them to 1970s Earth, where the travellers have to contend with stone circles, Druidic rituals, and a not-so-mythical goddess known as the Cailleach.
101	4	"The Androids of Tara"	Michael Hayes	David Fisher	9.1	25 November - 16 December 1978	5D
The quest for the fourth segment takes them to the planet Tara. The Fourth Doctor and Romana find themselves embroiled in the political games of the planet Tara, where doubles, android or otherwise, complicate the coronation of Prince Reynart.
102	5	"The Power of Kroll"	Norman Stewart	Robert Holmes	9.4	23 December 1978 - 13 January 1979	5E
The quest for the fifth segment takes them to the planet third moon of Delta Magna, caught in the middle of a dispute between the crew of a Methane Refinery and the natives (known as 'Swampies').
103	6	"The Armageddon Factor"	Michael Hayes	Bob Baker and Dave Martin	8.5	20 January - 24 February 1979	5F
The quest for the sixth and final segment takes them to Atrios, a world caught in a perpetual, stalemated war with its planetary neighbour Zeos. But the Black Guardian is closing in.

Broadcast

DVD Release

All serials of The Key to Time were released in a complete box set in 2009 and 2007